1. Field of the Invention
This invention relates generally to panning, tilting, and zooming in webcams, and more particularly, to the mechanical panning, tilting and zooming of video webcams controlled by software or firmware.
2. Description of the Related Art
Over the past few years, electronic contact between people has increased tremendously. Various modes of communication are used to electronically communicate with each other, such as video conferencing, emails, text messaging, etc. In particular, Instant Messaging (IM), which permits people to communicate with each other over the Internet in real time (“IM chats”), has become increasingly popular. More recently, video data is also being transmitted in conjunction with real time IM chats.
Several cameras exist which can be used for such electronic video communication. Some such cameras have the ability to capture still image data in addition to video data and audio data. For purposes of video real time chats, these cameras are often connected to a user's computer, and the video and/or audio data captured by the camera is transmitted to the computer. As mentioned above, several other applications may exist, where still image, video and/or audio data is transmitted, such as live video streaming, video capture for purposes of creating movies, video surveillance, internet surveillance, internet webcams, etc.
In such applications, seeing the face of the other user is often of paramount importance. For instance, in a case where two users are communicating using video IM, it is often desired that the impression of actually chatting with the other user is created. Thus seeing each other's faces greatly enhances this experience. It is, however, natural for people to move their faces from side to side, or up and down etc., and thus completely or partially disappear from the field of view of the camera. In such applications, it is thus often very important to track the face of the user.
However, most conventional cameras used for instant messaging (often webcams) do not move automatically to track a user's face. The user has to specifically move the camera by hand to re-enter the field of view, or has to consciously move his or her face back into the field of view of the camera. In some cases, optical face tracking has been implemented. One such camera which implements optical face tracking is the QuickCam Pro 4000® from Logitech, Inc. (Fremont, Calif.). As an example of how optical tracking may work, consider that the user's face moves to the top right corner of the field of view of the camera. The software associated with the camera may recognize this movement of the user's face, zoom in to the face, crop the image data around the face, and then resize the image being transmitted.
Optical face tracking has several limitations. First, the quality of such optically processing image data is significantly degraded. Second, the field of view of the camera is unchanged by such optical processing. Thus if the user were to move enough to go out of the current field of view of the camera, optical face tracking cannot compensate for this. U.S. Pat. No. 6,297,846 uses a wide angle lens, and from the wide angle image, follows people and chooses a window within the wide angle image.
Another solution is proposed in U.S. Pat. No. 5,598,209, entitled “Method for automatically adjusting a video conferencing system camera.” The patent discusses provides alternative methods of adjusting the pan, tilt, zoom and focus of a camera. However, the disclosed methods require specific input from the user regarding which object or which specific position around which the field of view of the camera should be centered. The panning, tilting, etc. is not automatic, based on tracking the face of the user.
Some patents describe still picture framing systems, and others use ranging systems to adjust to the distance by zooming. U.S. Pat. Nos. 6,606,458 and 5,864,363 describe automatic alignment of a person's face for a camera portrait, but do not provide continuous tracking for video. U.S. Pat. No. 5,389,967 shows tracking an object with a camcorder, but using an infrared signal. U.S. Pat. No. 4,348,097 shows a camera mounted on a track, with a distance gauge used to control movement of the camera to maintain a desired distance from an object.
U.S. Pat. No. 6,680,745 teaches multiple cameras for a video conference, with one wide angle camera detecting movement of people, and then directing the zoom, pan and tilt of other cameras. A similar system, with one camera controlling others, is shown in US published application no. 20020113862, which shows a wide angle camera, connected to a USB, controlling other cameras to follow faces. Some systems use sounds (the person talking) to locate a person who has moved out of a camera's range. Typically, a special video conferencing board is used, with a first cable providing the video input, and other cables providing the outgoing control to the cameras.